弯曲荷载下浪溅区混凝土中氯离子的扩散规律

Flexural Load-Affected Diffusion Rules of Chloride Through Concrete in Splash Zone

采用恒定弯曲荷载的方式,研究了应力水平对浪溅区海工高性能混凝土内氯离子扩散规律的影响,并采用SEM-EDS法和BET法分析了荷载对混凝土和浆体微观结构的影响.结果表明:在纯受弯段内,距暴露表面相同深度处的氯离子含量随着弯曲应力水平的增加而增大;对于典型的海工高性能混凝土配合比,混凝土试件的弯曲应力与恒定荷载影响因子之间呈近似指数函数关系,在混凝土结构耐久性设计中应考虑弯曲荷载对氯离子扩散系数的影响;弯曲应力水平的增加不仅会增大界面过渡区微裂缝的宽度,还会增加硬化浆体中毛细孔和大孔的比例,并最终引起总孔体积和平均孔径的增大,从而降低混凝土的抗氯离子渗透性能.

The influence of stress level on the diffusion rules of chloride through maritime high-performance concrete in splash zone was investigated under constant flexural load,and the load-affected microstructure of the concrete and the hardened paste was also analyzed by means of SEM-EDS and BET tests. The results show that（ 1） in the pure bending section,the content of chloride in the concrete at a given depth increases with the increase of the flexural load;（ 2） for typical maritime high-performance concrete mix,there is approximately an exponential correlation between the flexural load and the constant load factor,so that the influence of flexural load on chloride diffusion coefficient should be considered in the durability design of concrete structures;（ 3） the increase in flexural load not only widens the micro-cracks in the interfacial transition zone but also improves the proportion of capillary and macro pores in the hardened paste,and eventually results in the increase of the total pore volume and average pore size,thus decreasing the resistance of concrete to chloride ion penetration.